Various measurement mechanisms have been used to monitor various aspects of a railway system. Axle counter and wheel imbalance weighting system are two popular measurement mechanisms among them.
Conventionally, an axle counter uses magnetic fields to count the axles of a passing train, and a typical wheel imbalance weighting system uses a strain gauge sensor in a bridge circuit to measure the load of the train. Disadvantages exist with these conventional mechanisms, for example, installation of some conventional measurement mechanism may not be easy. More importantly, performance of these conventional mechanisms may be affected by external electromagnet radiation. This may deteriorate the reliability of these conventional measurement mechanisms, especially in an AC railway system, since lots of noises could be introduced to these conventional measurement mechanisms. In addition, these conventional measurement mechanisms need to be individually installed onto the railway. This may not be convenient if a significant number of measurement mechanisms are needed. Neither can it be convenient to set up a centralized railway monitoring system due to the complexity of collection of all the results from each individual measurement mechanism.